Sensitivity of horizontal grid resolution on the simulation of thunderstorms over Bangladesh using Weather Research Forecasting Model

Thunderstorms are a weather phenomenon characterized by lightning, thunder, and precipitation, and in Bangladesh, they are a common occurrence with the potential to cause significant damage to life and property. The objective of this study is to examine the sensitivity of the horizontal grid resolution of the WRF-ARW model for simulating thunderstorms in Bangladesh. Two cases from August 2022 were examined. The model was integrated over a 60-h period, with hourly outputs collected from August 16, 0000 UTC, to August 19, 1200 UTC, and two experiments were conducted using horizontal resolutions of 9 and 3 km. The results were validated using observational and ERA-5 reanalysis data. The findings showed that the 9-km resolution had better spatial agreement with ERA-5 for CAPE, although 3 km overestimated the maximum value compared to ERA-5. Thus, increasing the grid resolution will require more processing resources but will not always benefit the model’s efficiency for the given model setting. Higher grid resolution generally leads to better spatial accuracy because it captures more fine-scale features and processes in the atmosphere. Especially at coarse grid resolutions, fine-scale topography may be poorly represented or even completely smoothed out. However, the choice of physical parameterization schemes in the WRF model can affect its performance at different resolutions. Some parameterization schemes may perform better at coarser resolutions, while others may be more suitable for finer resolutions.